Studies in Binocular Vision have proceeded along two parallel tracks: psychophysics and neuroanatomy. The psychophysical work capitalizes on stereoblindness as a technique for dissecting the normal stereoscopic mechanism. During the past year, the principal psychophysical finding is that the elimination of monocular cues to stereopsis can lead to deficits resembling stereoblindness. Monocular cuing is an inherent feature of the normal stereoscopic mechanism. On the second track, neuroanatomical studies reinforce our earlier finding that crosseyedness in the ordinary (non-Siamese) cat is correlated with two aberrations in the visual pathway. The two key factors are hemispheric asymmetries in the visual cortices and the lack of a midbrain commissure in the pretectal region.